This invention relates to a method for extracting, fractionating and purifying compounds originating from leafy edible plants of the Compositae family or bulb plants of the Liliaceae family or from sorting deviations of fresh plants in order to obtain an extract comprising polyphenolic compounds.
More particularly, the invention provides a method for extracting, fractionating and purifying polyphenolic compounds, wherein the purification is performed by polyphenolic compound adsorption on an adsorbing resin, followed by the elution of the compounds retained on the resin.
According to the invention, it is meant by extract comprising phenolic compounds a product having a polyphenolic compound minimum content equal to or higher than 30% based on the dry weight.
According to the invention, it is meant by purification the recovery or the selection of the extracted phenolic compounds.
Methods for extracting and purifying the polyphenolic compounds in plant materials using an adsorbing resin are known in the prior art.
U.S. Pat. No. 5,994,413 relates to a method for extracting polyphenolic compounds from Rosaceae fruit, such as apples, pears, peaches and related fruits. This patent more particularly discloses a polyphenolic compound isolation and purification method from fruit using juice extraction from peeled or non peeled fruit, crushing the fruit, followed by centrifugation and recovery, followed with the passage of the juice thus obtained on a resin able to selectively retain the phenolic compounds and finally the elution of the polyphenols retained on the resin so as to obtain a powder comprising phenolic compounds. This patent mentions several adsorbants, such as synthetic styrene-divinyl benzene resins, anion exchange resins or silica gels on which are chemically fixed the octadecyl groups, the elution of the polyphenols adsorbed on these resins being performed by adding an alcohol solution, such as ethanol.
U.S. Pat. No. 5,141,611 discloses a method allowing to eliminate the polyphenolic substances contained in a solution, and, optionally, to recover them using a polyamid resin on which the polyphenols are adsorbed.
U.S. Pat. No. 5,856,429 relates to a method for removing polyphenols from liquids, wherein the polyphenols are retained on an amid resin. This patent also discloses other types of polyphenol adsorbing medium, such as Nylon or polyvinylpolypyrrolidone (PVPP).
U.S. Pat. No. 4,910,182 discloses a method for stabilizing drinks containing polyphenols wherein an adsorbing polyvinylpolypyrrolidone (PVPP) medium is used. Such a method is particularly adapted for elimination of polyphenolic compounds from beer.
U.S. Pat. No. 4,800,339 relates to a method for eliminating polyphenols from vegetable origin drinks such as beers, wines and fruit juices, using a N-substituted polyamid based adsorbing resin.
These methods, however, have the disadvantage that they use resins that either have a high adsorption performance or a high elution performance, but that do not simultaneously have both a high adsorption performance and a high elution performance.
An object of the present invention therefore is to provide a method for extracting, fractionating and purifying polyphenolic compounds, removing the prior art drawbacks.
In particular, an object of the present invention is to provide a method for extracting, fractionating and purifying comprising a step for extracting the polyphenolic compounds originating from leafy edible plants of the Compositae family or bulb plants of the Liliaceae family or plants of the rosaceous family or the sorting residues thereof, or from sorting deviations of fresh plants, an adsorption step followed with an elution step of such compounds using a resin having particular physical features, giving it a high adsorption ability of the polyphenolic compounds and a high elution ability.
Another object of said invention is to provide a product comprising polyphenolic compounds using the method of the invention.
Another object of the invention is to provide the use of a product such as defined here-above for making cosmetics and/or pharmaceutical compounds and/or food ingredients.
The aims of the present invention are therefore achieved by a method for extracting, fractionating and purifying polyphenolic compounds originating from leafy edible plants of the Compositae family or bulb plants of the Liliaceae family, or from sorting deviations of fresh plants, comprising the following steps of:
a) extracting the polyphenolic compounds in order to obtain a raw plant material extract,
b) adsorbing on an adsorbing resin the polyphenolic compounds contained in the raw extract,
c) eluting the polyphenolic compounds retained on the resin in order to obtain a purified extract, and
d) concentrating, optionally followed by drying, the purified extract in order to obtain a product comprising polyphenolic compounds,
wherein the resin is a styrene-divinyl benzene resin having the following physical features:
1) pores with an average size in the range from 50 to 110 angstroms, preferably from 60 to 100 angstroms,
2) a surface area equal to or higher than 800 m2/g, preferably equal to or higher than 880 m2/g, giving the resin an organic particle high adsorption ability,
3) a pore volume higher than 1 ml/g, and preferably equal to or higher than 1.4 ml/g.
Preferably, the resin according to the invention has the following physical features:
1) pores with an average size in the range from 80 to 110 angstroms, preferably from 88 to 92 angstroms, and more preferably about 90 angstroms,
2) a surface area equal to or higher than 1000 m2/g, preferably equal to or higher than 1200 m2/g,
3) a pore volume equal to or higher than 2 ml/g, and preferably equal to or higher than 2.4 ml/g.